Studies on the role(s) of bone tRNA methyltransferases in skeletal metabolism will be continued. Dose-response relationships between hormones and bone tRNA methyltransferases will be investigated. Also persistence of changes in enzyme activities following administration in vivo of hormones known to affect skeletal metabolism will be determined. The interrelation between the adenylcyclase system and bone tRNA methyltransferases will be examined in greater detail. The effects of alterations in vivo of Ca ions, Mg ions and PO4 ions on bone tRNA methyltransferases will also be studied.